42
Longnose Skate
Raja rhina
dorsal
ventral
egg case
Nuchal Orbital Dorsal diagram showing thorns on disc.
Diagnosis The only Alaska species
of Raja with an elongate snout and
deeply notched pelvic fins.
Denticles Fine denticles on dorsal
surface; ventral surface smooth.
Coloration Dorsal surface brown with
dark blotches; may have ocelli on disk;
ventral surface gray to black.
Reproduction Oviparous. Egg case
large and smooth; large webbed keels
on posterior and anterior margins;
horns short, with a loose ventral curl.
Egg case maximum size is 154 mm long
by 121 mm wide.
Maximum Size At least 142 cm. NMFS
records up to 180 cm are not verifiable.
Range Eastern Bering Sea to Baja
California and Gulf of California.
Depth 9-1,069 m.
Remarks The longnose skate is
another large species common in the
Gulf of Alaska. It is generally found in
deeper waters than the big skate, and
is only very rarely encountered in the
southeastern Bering Sea.
In Alaska waters, the longnose skate is found in
the Gulf of Alaska and southeastern Bering Sea.
Similar Species The longnose skate is
most likely to be confused with the big
skate, but can be distinguished by its
prolonged snout and deeply notched
pelvic fins. Unlike the big skate, it also
has a small dark ocellus on the dorsal
surface of each pectoral fin and a
relatively dark ventral surface.
Longnose Skate Raja rhina
43
44
Alaska Skate
Bathyraja parmifera
dorsal
ventral
egg case
Nuchal Orbital Scapular Mid-dorsal
Dorsal diagram showing thorns on disc.
Diagnosis The only Alaska species
of Bathyraja with the following
combination of characters: naked area
surrounding the tail thorns; orbital
thorns and scapular thorns present
(orbital thorns may be reduced); dorsal
surface dark brown or golden brown,
often with lighter spots or blotches;
total midline thorns typically 32 or
less. Row of mid-dorsal thorns may be
complete or interrupted.
Denticles Evenly distributed on dorsal
surface of juveniles, patchy on adults;
ventral surface smooth.
Coloration Dorsal surface dark brown
or golden brown, often with lighter
spots or blotches; ventral surface
brown to white.
Reproduction Oviparous. Egg case
large, with rows of smooth low ridges
and wide keel; byssal threads attached
on anterior horns. Egg case maximum
size is 140 mm long by 107 mm wide.
Maximum Size 135 cm.
Range Bering Sea, Aleutian Islands,
Gulf of Alaska; western Bering Sea to
Japan.
Depth 17-392 m.
Remarks The Alaska skate is perhaps
the most common skate in Alaska
waters. It is virtually the only species
of skate found on the Bering Sea shelf,
where it can be locally abundant. It
appears to be uncommon in the Gulf
of Alaska, particularly east of Kodiak,
and is replaced in the western Aleutian
Islands by the “leopard skate” (see
p. 46).
In Alaska waters, the Alaska skate is found in the
Gulf of Alaska, Bering Sea, and eastern Aleutian
Islands.
Similar Species The Alaska skate is
most similar to the leopard skate from
which it differs in coloration. In the
western Aleutians, the dorsal surface of
the leopard skate exhibits a vivid oliveyellow leopard spotting pattern and
the total midline thorn count is usually
higher (31 or more).
Alaska Skate Bathyraja parmifera
45
46
“Leopard Skate”
Bathyraja sp. cf. parmifera
dorsal
ventral
egg case
Nuchal Orbital Scapular Mid-dorsal
Dorsal diagram showing thorns on disc.
Diagnosis The only Alaska species
of Bathyraja with the following
combination of characters: naked area
surrounding the tail thorns; orbital
thorns and scapular thorns present
(orbital thorns may be reduced); dorsal
surface olive green with many dark
spots or blotches and brighter yellow
patches; total midline thorns typically
31 or more.
Denticles Evenly distributed on dorsal
surface of juveniles, patchy on adults;
ventral surface smooth.
Coloration Dorsal surface olive green
with many dark spots or blotches and
brighter yellow patches; ventral surface
gray to white.
Reproduction Oviparous. Egg
case large, with rows of smooth low
ridges and wide keels; byssal thread
attachment at anterior margin. Egg
case maximum size is 128 mm long by
98 mm wide.
Maximum Size 139 cm.
Range Western Aleutian Islands.
Depth 48-396 m.
Remarks The leopard skate is
currently an undescribed species, soon
to be formally named by the authors,
which appears to be restricted in
Alaska waters to the Aleutian Islands
in Amchitka Pass and farther west.
In addition to body shape and color
differences, recent genetic studies
provide additional evidence that it is a
distinct species closely related to the
Alaska skate.
The leopard skate is known only from the western Aleutian Islands.
Similar Species The leopard skate is
most similar to the Alaska skate, from
which it differs primarily in coloration.
The dorsal surface of the Alaska skate
is dark or golden brown, often with
lighter spots or blotches, and the total
midline thorn count is usually lower (32
or less).
“Leopard Skate” Bathyraja sp. cf. parmifera
47
48
Bering Skate
Bathyraja interrupta
ventral
dorsal
Nuchal Scapular (Mid-dorsal)
egg case
Dorsal diagram showing thorns on disc.
Diagnosis The only Alaska species
of Bathyraja with the following
combination of characters: orbital
thorns absent; scapular thorns present;
row of mid-dorsal thorns usually
interrupted; tail thorns reduced, with
0-2 reduced thorns between dorsal fins.
Denticles Evenly distributed on dorsal
surface; ventral surface smooth.
Coloration Dorsal surface light to dark
brown; ventral surface white.
Reproduction Oviparous. Egg case of
moderate size, with smooth low ridges;
keel wide at mid-case, tapering on
horns; byssal threads attached at midcase and/or base of posterior horns;
currently indistinguishable from egg
cases of Bathyraja violacea; egg cases
show considerable variation across the
species range. Egg case maximum size
is 95 mm long by 75 mm wide.
Maximum Size 86 cm.
Range Bering Sea, eastern Aleutian
Islands, Gulf of Alaska, to California.
Depth 26-1,050 m.
Remarks This form is probably not a
single species, but a species complex
that extends from the western Bering
Sea to southern California. In the
southern part of its range, it is generally
known as the sandpaper skate. Future
taxonomic work hopefully will resolve
this issue.
Similar Species The Bering skate
exhibits a great deal of variation in
the prominence of the thorns on the
disc. Some specimens have greatly
reduced thorns, and can therefore
be misidentified as mud or Okhotsk
skates. Specimens with well-developed
thorns may be misidentified as Alaska
or Aleutian skates, but differ from the
In Alaska waters, the Bering skate is found in the
Gulf of Alaska, Bering Sea, and eastern Aleutian
Islands.
former in having denticles surrounding
the tail thorns and from the latter in
having a reduced or interrupted middorsal thorn row as well as reduced
interdorsal thorns.
Bering Skate Bathyraja interrupta
49
50
Aleutian Skate
Bathyraja aleutica
dorsal
ventral
egg case
Nuchal Scapular Mid-dorsal
Dorsal diagram showing thorns on disc.
Diagnosis The only Alaska species
of Bathyraja with the following
combination of characters: orbital
thorns absent; scapular thorns present;
row of mid-dorsal thorns usually
continuous; tail thorns large, with 1 or 2
strong thorns between dorsal fins.
Denticles Evenly distributed on dorsal
surface; ventral surface smooth.
Coloration Dorsal surface gray, with
or without vague black ocellus on
pectoral fin; ventral surface white with
gray margin.
Reproduction Oviparous. Egg case
large, covered in brownish bristles that
form a fur-like mat; keel narrow, thick,
opaque at mid-case; byssal threads
attached distally on posterior horn. Egg
case maximum size is 146 mm long by
100 mm wide.
Maximum Size 161 cm.
Range Bering Sea, Aleutian Islands,
and Gulf of Alaska to northern
California; western Bering Sea to Japan.
Depth 15-1,602 m.
Remarks The Aleutian skate is one
of the most widespread skates in
Alaska, both geographically and
bathymetrically. It is particularly
common in the Aleutian Islands.
Similar Species The Aleutian skate’s
thorn pattern most closely resembles
those of the Bering, Alaska, and
“leopard” skates. However, the Aleutian
skate can be distinguished from the
Bering skate by the strength of the
mid-dorsal and interdorsal thorns, and
from the Alaska and leopard skates
by the presence of denticles around
the tail thorns. The coloration of the
Aleutian skate may be vaguely similar
to that of the whiteblotched skate, but
the thorn pattern is markedly different.
In Alaska waters, the Aleutian skate is found
in the Gulf of Alaska, Aleutian Islands, and
Bering Sea.
Aleutian Skate Bathyraja aleutica
51
52
Okhotsk Skate
Bathyraja violacea
dorsal
ventral
egg case
Dorsal diagram showing absence of disc thorns.
Diagnosis The only Alaska species
of Bathyraja with the following
combination of characters: disc free
of thorns; large diamond-shaped disc,
with tail length less than or equal
to precaudal length; dorsal surface
without pale or yellow blotches; ventral
surface white or cream-colored.
Denticles Dorsal surface with patches
of small fine denticles; ventral surface
smooth.
Coloration Dorsal surface gray to
brown, often with dark reticulations;
ventral surface white or cream-colored.
Reproduction Oviparous. Egg case of
moderate size, with smooth low ridges;
keel wide at mid-case, tapering on
horns; byssal threads attached at midcase and/or base of posterior horns;
presently indistinguishable from egg
cases of the Bering skate.
Maximum Size 73 cm.
Range Western Aleutian Islands;
western Bering Sea to Japan.
Depth 124-510 m.
Remarks The distribution of this
species is poorly known, but it appears
to be much more common in the
western Bering Sea and Sea of Okhotsk.
It can be difficult to distinguish from
the Bering skate.
In Alaska waters, the Okhotsk skate is known
from only one location.
Similar Species The Okhotsk skate
generally has no thorns on the disc,
and therefore can be confused with the
mud skate or butterfly skate. However,
the mud skate is smaller and rounded,
and males have a pseudosiphon on
the clasper. In the Aleutians, both the
mud skate and the butterfly skate
can easily be distinguished from the
Okhotsk skate by the presence of vivid
greenish or yellow blotching on the
disc. The Bering skate occasionally has
greatly reduced thorns, and also can be
confused with the Okhotsk skate.
Okhotsk Skate Bathyraja violacea
53